Belt drive systems transmit power via a V-belt by wrapping the V-belt around a V-pulley and frictionally engaging them. There is known a V-belt for such a belt drive system that has a structure in which a large number of blocks are fitted on a pair of tension members. When the V-belt has such a structure, a problem arises that noise during belt travel is relatively large. Specifically, when the V-belt moves into and away from the V-pulley, each block of the V-belt comes into contact with the surface of the V-pulley to produce an impact sound. On the other hand, when each block disengages from the V-pulley, it produces a sticking sound.
Known structures for reducing such noise during belt travel include a structure in which the surface roughness of the groove surface of the V-pulley is adjusted to a predetermined arithmetic mean roughness Ra, as disclosed in Patent Document 1, and a structure in which a shell member is disposed on the pulley groove surface, as disclosed in Patent Document 2.
Specifically, Patent Document 1 discloses a technique of adjusting the surface roughness of the groove surface of the V-pulley to a predetermined arithmetic mean roughness Ra to reduce energy generating by interference between the V-belt and the V-pulley in contact with each other, thereby reducing noise during belt travel.
Patent Document 2 discloses a technique in which a sheet-like shell member formed in a substantially lambdoid cross section is disposed to cover the entire groove surface of the V-pulley and a buffer material or liquid placed between the shell member and the groove surface of the V-pulley absorbs energy generating during contact of the V-belt with the V-pulley to reduce noise during belt travel.
Patent Document 1: Published Japanese Patent Application No. 2002-70992
Patent Document 2: Published Japanese Patent Application No. H10-122318